LTC4274A/LTC4274C - Single PoE/PoE+/LTPoE++ PSE Controller


  • Compliant with IEEE 802.3at Type 1 and 2
  • Low Power Dissipation
  • 0.25Ω Sense Resistance Per Channel
  • Very High Reliability 4-Point PD Detection
  • 2-Point Forced Voltage
  • 2-Point Forced Current
  • High Capacitance Legacy Device Detection
  • 1MHz I2C Compatible Serial Control Interface
  • Midspan Backoff Timer
  • Supports 2-Pair and 4-Pair Output Power
  • Available in Multiple Power Grades
  • LTC4274A-1: LTPoE++™ 38.7W
  • LTC4274A-2: LTPoE++ 52.7W
  • LTC4274A-3: LTPoE++ 70W
  • LTC4274A-4: LTPoE++ 90W
  • LTC4274C: PoE 13W
  • Available in 38-Lead 5mm × 7mm QFN Package

Typical Application

LTC4274A_C Typical Application


The LTC®4274A is a single Power Sourcing Equipment (PSE) controller capable of delivering up to 90W of LTPoE++ power to a compatible LTPoE++ Powered Device (PD). A proprietary detection/classification scheme allows mutual identification between a LTPoE++ PSE and LTPoE++ PD while remaining compatible and interoperable with existing Type 1 (13W) and Type 2 (25.5W) PDs. The LTC4274A feature set is a superset of the popular LTC4274. These PSE controllers feature low-RON external MOSFETs and 0.25Ω sense resistors which are especially important at the LTPoE++ current levels to maintain the lowest possible heat dissipation.

The LTC4274C targets fully automatic PSE systems powering Type 1 (up to 13W) PDs.

Advanced power management features include: a 14-bit current monitoring ADC, DAC-programmable current limit, and versatile quick port shutdown. PD Discovery uses a proprietary dual-mode 4-point detection mechanism ensuring excellent immunity from false PD detection. The LTC4274A/LTC4274C includes an I2C serial interface operable up to 1MHz.

The LTC4274A/LTC4274C is available in multiple power grades, allowing delivered PD power of 13W, 25.5W, 38.7W, 52.7W, 70W and 90W. These controllers are available in a 38-lead 5mm × 7mm QFN package.


CAD Symbols and Footprints: The downloadable Zip file below contains the schematic symbol and PCB footprints.

For complete and up to date package information and drawings, please refer to our packaging page

Part Number Package Code Temp Package
LTC4274AIUHF-1#PBF 5x7 QFN-38 UHF I 05-08-1701 Yes
LTC4274AIUHF-1#TRPBF 5x7 QFN-38 UHF I 05-08-1701 Yes
LTC4274AIUHF-2#PBF 5x7 QFN-38 UHF I 05-08-1701 Yes
LTC4274AIUHF-2#TRPBF 5x7 QFN-38 UHF I 05-08-1701 Yes
LTC4274AIUHF-3#PBF 5x7 QFN-38 UHF I 05-08-1701 Yes
LTC4274AIUHF-3#TRPBF 5x7 QFN-38 UHF I 05-08-1701 Yes
LTC4274AIUHF-4#PBF 5x7 QFN-38 UHF I 05-08-1701 Yes
LTC4274AIUHF-4#TRPBF 5x7 QFN-38 UHF I 05-08-1701 Yes
LTC4274CIUHF#PBF 5x7 QFN-38 UHF I 05-08-1701 Yes
LTC4274CIUHF#TRPBF 5x7 QFN-38 UHF I 05-08-1701 Yes

LTC4274A_C Package Drawing

Order Info

  • Part numbers ending in PBF are lead free. Solder plated terminal finish (SnPb) versions are non-standard and special terms and conditions and pricing applies if available. Please contact LTC marketing for information.
  • Part numbers containing TR or TRM are shipped in tape and reel or 500 unit mini tape and reel, respectively
  • Please refer to our general ordering information or the product datasheet for more details

Package Variations and Pricing

Part Number Package Temp Price
LTC4274AIUHF-1#PBF 5x7 QFN-38 I $7.71 $5.40 Yes
LTC4274AIUHF-1#TRPBF 5x7 QFN-38 I $5.46 Yes
LTC4274AIUHF-2#PBF 5x7 QFN-38 I $7.71 $5.40 Yes
LTC4274AIUHF-2#TRPBF 5x7 QFN-38 I $5.46 Yes
LTC4274AIUHF-3#PBF 5x7 QFN-38 I $7.71 $5.40 Yes
LTC4274AIUHF-3#TRPBF 5x7 QFN-38 I $5.46 Yes
LTC4274AIUHF-4#PBF 5x7 QFN-38 I $7.71 $5.40 Yes
LTC4274AIUHF-4#TRPBF 5x7 QFN-38 I $5.46 Yes
LTC4274CIUHF#PBF 5x7 QFN-38 I $6.43 $4.50 Yes
LTC4274CIUHF#TRPBF 5x7 QFN-38 I $4.56 Yes
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* The USA list pricing shown is for BUDGETARY USE ONLY, shown in United States dollars (FOB USA per unit for the stated volume), and is subject to change. International prices may differ due to local duties, taxes, fees and exchange rates. For volume-specific price or delivery quotes, please contact your local Linear Technology sales office or authorized distributor.

Demo Boards

Linear Technology offers many demo boards free of charge to qualified customers. Contact your local sales office or distributor to inquire about a demo board. Certain demo boards are also available for sale via credit card on this website. Demo boards are for evaluation purposes only. It remains the customer’s responsibility to verify proper and reliable operation in the actual end application.

Part Number Description Price Documentation
DC1814A-A LTC4274A-1 Demo Board | LTPoE++ (38.7W) PSE $100.00
DC1814A-B LTC4274A-2 Demo Board | LTPoE++ (52.7W) PSE $100.00
DC1814A-C LTC4274A-3 Demo Board | LTPoE++ (70W) PSE $100.00
DC1814A-D LTC4274A-4 Demo Board | LTPoE++ (90W) PSE $100.00
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Companion Boards

Part Number Description Price Documentation
DC2046A-E LT4276A/LT4321 Demo Board | LTPoE++ (38.7W, 5V/7A) PD with DC/DC and Ideal Diode Bridge $95.00
DC2093A-A LT4275A/LT4321 LTPoE++/PoE+/PoE PD Demo Board $95.00
DC2262A-A LT4276A/LT4321 Demo Board | LTPoE++ (70W, 5V/13A) PD with DC/DC and Ideal Diode Bridge $95.00
DC2262A-B LT4276A/LT4321 Demo Board | LTPoE++ (90W, 12V/7A) PD with DC/DC and Ideal Diode Bridge $95.00
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Click here to view our complete list of demo boards


  • LTPoE++ PSE Switches/Routers
  • LTPoE++ PSE Midspans
  • IEEE 802.3at Type 1 PSE Switches/Routers
  • IEEE 802.3at Type 1 PSE Midspans

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